1. Field of the Invention
The present invention relates to an ink jet recording head for recording images and characters on recording paper by emitting ink droplets from nozzle apertures by the expansion and contraction of piezoelectric vibrators operating in a longitudinal vibration mode.
2. Background
It is known to use a recording head having piezoelectric vibrators which operates in a longitudinal vibration mode and which can be driven at a high speed. Such a recording head includes a passage unit formed by laminating a nozzle plate having nozzle apertures, a passage forming plate having pressure generating chambers and reservoirs, and an elastic plate. The recording head is driven by a vibrator unit including piezoelectric vibrators which expands and contracts in its longitudinal direction with one end of the vibrator being fixed to a fixing base.
With such a vibrator unit, since the rigidity of the vibrator itself is high, the area of the contact surface with the pressure generating chamber can be reduced and the vibrator unit will still be suitable for a recording head designed for high density printing. However, when high density printing is desired, there are the following concerns: (1) the array pitch is extremely small; (2) the reaction force which operates on a fixing base is extremely large; (3) the amount of deflection of the fixing base is varied depending upon the number of simultaneously driven piezoelectric vibrators; and (4) the capacity of the emission of ink droplets depends upon the number of simultaneously driven piezoelectric vibrators.
To address these concerns, measures have been taken, such as providing a fixing base made of a very rigid material and a reinforcement member, such as metal, inserted between a frame for integrally fixing the passage unit and the vibrator unit. However, there is a problem associated with this solution in that the fixing base is too large and the assembly is complicated.